In the northern regions of Alberta, Canada, are oil sands from which bitumen is extracted using a hot water extraction process and upgraded using a hydroconversion process. Deleteriously, the sulfur content of the produced coke is high, of the order of 6-9% wt. Thus, when such coke is combusted, the sulphur dioxide emissions are above permissible limits, rendering the coke useless as a solid fuel. Since 1975, researchers have unsuccessfully sought methods of reducing the sulfur dioxide released upon the combustion of the cokes produced by the refinery. Unfortunately, up to the present time the coke, which is useless, is stockpiled until such time that a treatment process is arrived at.
Various processes for the control of sulfur dioxide emissions during petroleum coke combustion have been disclosed in the literature and patents. Exemplary disclosures would include those of U.S. Pat. No. 4,302,207 or U.S. Pat. No. 4,515,601.
The '207 patent issued to S. C. Paspek, teaches the use of an aqueous gelling agent with coal and a calcium-containing compound as a sulphur getter. The utilization of an aqueous component inherently will result in a lowered fuel efficiency in comparison to using a non-aqueous gelling agent.
The '601 patent issued to J. E. Charters discloses briquette agglomerates formed from pulverized coke, sand, dolomite, clay and asphaltene. Bentonite is used as the binding agent. However, dolomite has the disadvantage of being difficult to grind, and a proportionately large amount would be required in order to provide effective sulfur capture.
It is to be noted, however, that the sulfur capture efficiency of the fuels produced from either of the above teachings, deleteriously, would only range between 9 to 75% at combustion temperatures ranging between 500.degree. C. to 800.degree. C.
There exists, therefore, always, the requirement to find a fuel having a higher sulfur capture efficiency at the temperatures at which conventional furnaces are operated, namely between 700.degree. C. and 800.degree. C.
Additionally, the disadvantages of many of these prior art processes are that they are not considered to be sufficiently economically attractive for use on a commercial scale.
Along somewhat different lines, though of relevance to the background of the instant invention, it is known in the art to form coke or coal agglomerates. Such agglomerates have been prepared using `wet` techniques wherein water, bitumen (and/or an alternative liquid hydrocarbon) and coke are admixed. These formed agglomerates, following separation from the water, may then be used as fuel. The disadvantages of these prior art agglomeration techniques are that very large amounts of water and extensive agitation are required to prepare the agglomerates. Furthermore, agglomerates thus formed are not easily handled, exhibiting mechanical instability and the like. It would be advantageous, therefore, to provide an agglomeration process which would yield mechanically stable agglomerates and avoid the use of water.